Dissemination of reference AC/DC voltage difference between ranges of AC/DC transfer standard

The measurement of low voltage up to 1000 V with a frequency of up to 1 MHz is crucial in electricity and magnetism. The AC/DC voltage transfer difference (AC/DC difference) is a critical metrological characteristic of the reference thermal converter. The metrological traceability of electrical voltage measurements shall be validated by either comparison with other national standards or calibration using standards with lower measurement uncertainty. Since, in practice, the period between comparisons of national standards is not always appropriate, calibration is more suitable for establishing metrological traceability if a primary standard is not introduced. This paper shows the way how to address the issue of irregular calibration of the component (Fluke 792A instrument) of the state standard DETU 08-07-02, detailing the approach to disseminate the reference AC/DC difference. Features of the mentioned measuring instrument are outlined, and ranges of voltage comparison are analysed, including one more suitable for being a link between the AC/DC difference and other measurement ranges. The diagram for disseminating the reference AC/DC difference demonstrates the proposed approach. The applied approximation allows one to deduce relations between the output quantity (AC/DC difference) of the studied standard and the input voltage depending on frequency for each input range. Using the mathematical processing program Microsoft Excel, the approximate equations were obtained, including polynomial dependence coefficients and coefficients of determination. In addition, by extrapolating the results of comparing the AC/DC differences it is possible to observe the potential bias in the controlled quantity.